1. Field of the Invention
The invention relates to pumps and motors of smallest constructional size, in the following referred to as one of micropump and micromotor. The terms designating orders of magnitude, being of a diameter range below 10 mm, particularly less than 3 mm. Such pumps may find manifold uses in the technical and medical sectors, for instance in microsystems engineering in dosing apparatuses, in medical engineering, as a drive means for one of a micro milling cutter and a bloodstream support pump.
2. Prior Art
Prior art is rich of specifications regarding the principle and the function of gear pumps having an inner wheel and an outer wheel, the wheels being in mating/meshing engagement (compare DE-A 17 03 802, claim 1, page 4, last paragraph and page 6, last paragraph, disclosing radially directed inflow and outflow channels). These operational units to be used as one of pumps and motors are characterized by having two axes, one axis of an inner rotor and another axis of an outer rotor, which axes are offset with respect to each other, and which rotors being in meshing engagement to circumferentially form pressure spaces (pressure chambers) cyclically changing their size and position.
The object of the invention is to provide a micropump of a minimum constructional volume, with which pump a continuous flow of a fluid to be conveyed is achieved and at the same time a high conveying capacity and a high feed (discharge) pressure are obtained.
Said object is achieved with a micropump, wherein an outlet pressure opening of a face end insert part for a sleeve casing of slightly larger diameter is adapted to extend in an axial direction. An inlet opening of a second face end insert part for the sleeve casing of slightly larger diameter may also be adapted to extend in axial direction. Thus, the entire pump is in a position to generate a continuous flow of fluid in axial direction, which flow is oriented to a circumferential direction only in an inner portion of the pump, where the rotors are in meshing engagement to circumferentially displace the pressure chambers. As soon as the flow of fluid to be conveyed enters the face end insert part on the outlet side, it is discharged from there in the axial direction through a pressure opening extending in axial direction. The pressure opening may consist of a number of individual bores arranged at circumferential intervals, it may consist of one single bore and it may be provided by one bore together with a kidney-shaped receiving groove on the inside surface of the outlet insert part.
The advantage of the pumps provided according to the invention is that, despite their almost unimaginable miniaturization, they are of a simple structure. An assembly of the micropump being available by a manufacturing method, wherein substantially cylindrical parts as components being assembled in a uniaxial direction. The two end insert components, being inserted in axial direction, are positioned at both ends of the sleeve casing, while the meshing wheels (inner rotor and outer rotor) which are likewise inserted in (the same) axial direction are interposed axially between them.
The pump is driven for example on an extended end portion of the shaft of the inner rotor or radially via the casing by one of a mere mechanical and electromechanical force. If an electromechanical drive force is used, e. g. one of the outer rotor and the sleeve casing may for a far reaching miniaturization be provided with integrated magnets, to serve as a rotor of a synchronous drive, the radially outer sleeve casing, which has a further outside radial position, permitting a penetration of electromagnetic fields.
Advantageously, slight conveying losses resulting from circumferential inexactnesses are used as a bearing for each respective rotatable component in the casing.
A motor for driving the pump is also characterized by being of smallest constructional size, simultaneously providing a high power density and even presenting a favorable characteristic line (torque in relation to speed). If the number of revolutions is not too high, the motor achieves a torque permitting to drive a pump without gearing. The driving energy of the motor is generated by a fluidic flow, passing the meshing wheels (inner rotor and outer rotor) and being discharged to the environment at the outlet side. A drive fluid enters through an inlet tubing or connection piece which is adapted to be fixedly mounted at the sleeve casing of the insert part or at the insert part itself.
When mounted at the face end insert, said insert may be slightly to markedly extended in relation to the sleeve casing to provide a firm fit for the inlet tubing.
The mounting of the inlet tubing implicates that the inlet tubing has about the same diameter as the micromotor.
If a fluidic drive is used, there is no difficulty with regard to an electric insulation for smallest constructional sizes. The fluidic drive medium may simultaneously serve as coolant, lubricant, rinsing medium and bearing fluid.
The motor consists of the same components as the pump, only different operational elements are one of fixedly and rotatably connected with each other. When uniaxially assembling the mentioned operational elements, a number of embodiments are provided to realize the motor and the pump, depending on which part is fixedly mounted on which, which part is rotatably mounted on which and which part the arrangement uses as a support on a fixed position. Using an inlet tubing as drive, the inlet tubing itself is the support. Driving the pump by an extended shaft portion, an elongated drive shaft is used.